Charles e



(No Model.)

. O. E. SORIBNER. MULTIPLE SWITGHBOARD SYSTEM FOR TELEPHONE EXCHANGES.

Patented Jan. 7, 1896.

3 Iva/671,207.-

ZesEScri/Zner- NITED STATES PATENT FFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WVESTERNELECTRIC COMPANY, OF SAME PLACE.

MULTIPLE-SWITCHBOARD SYSTEM FOR TELEPHONE-EXCHANGES.

SPECIFICATION forming part of Letters Patent No. 552,724, dated January7, 1896.

Application filed March 17, 1892.

To call whom it may concern.-

Be it known that I, CHARLES E. SCRIBNER, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in Multiple-SwitchboardSysterms for Telephone-Exchanges, (Case No. 290,)

' of which the following is a full, clear, concise,

and exact description, reference being had to the accompanying drawing,forming a part of this specification.

My invention relates to telephone-exchange systems, and moreparticularly to the individual annunciators and their circuits. Theindividual annunciator is provided with two armatures, one armatureserving as the drop or target and the other armature being provided witha hooked lever or detent, which is held in engagement with the drop. IWhen the subscriber sends current over the line,

the armature carrying the hooked lever is attracted sufliciently torelease the hook from the shutter and the shutter falls. Thiscurrentfrom the generator is not of sufficient strength to hold up thesoft-iron drop and prevent it from falling, and hence the shut terfalls, as before stated, when the subscriber operates his generator tosend current over the line through the individual annunciator. Batteryis provided in connection with the strands of the pairs of cords and soarranged that when the operator plugs into the switch of a line abattery current of considerable strength will be caused to flow throughthe individual annunciator of the line with which connection is thusmade. This current will be strong enough to cause the soft-iron drop tobe held in position by the attraction of the electromagnet. Thus asubscriber sends in a call, throwing down his annunciator. The operatorsees the shutter fall, inserts a plug in the switch of the callingsubscribers line, and at the same time restores the shutter by hand. Thebattery-current, which is thus automatically closed through theelectromagnet, will be of sufficient strength to hold up the softirondrop, notwithstanding the fact that at the same time the other armaturewill be attracted Serial No. 425,305. (No model.)

and the hook held out of engagement with the drop. The circuits are soarranged that the subscriber in signaling the central office sendscurrent through the limb of the metallic circuit which is connected withthe testpieces of the switches upon the switchboard, and which limb isprovided with apermanent ground connection at each end. On the otherhand the central office on depressing a calling-key to call up asubscriber loops the generator into a metallic circuit, including bothlimbs of the line of the subscriber who is be ing called.

My invention will be more readily understood by reference to theaccompanying draw- 4 The drawing illustrates two metallictelephone-circuits, each extending from the subscribers station thereofto the central office, and including each its individual annunciator atthe central office, together with a set of cords and plugs at each ofthe two switchboards with which the lines are connected. Station 1 isprovided with a metallic-circuit telephone -line a, which is connectedwith switches b c on different switchboards, the portion or limb of theline which connects with the test pieces or frames of the switches beingextended through an individual annunciator d to ground. The othersub-station 2 is connected by a similar line 6 to springjacks f 9 uponthe same switchboards, and with an individual annunciator it upon one ofthe switchboards. As shown in the'drawing, these two stations 1 and 2are connected together between their switches c g by means of the plugst' 7:; and the pair of cords connected therewith. An ordinarylistening-key Z is provided for bridging the .operators telephonebetween the strands of the cords. Usual calling-keys m n are provided inconnection witheach cord for looping the generator into the circuit of aline to call up the subscriber with which the plug of the cord isconnected.-

In connectionwith the pair of cords shownat the first board that is, theboard on which 5 switches 17 f are supposed to be placed-I have shownthe calling-generator 0 and the connections thereof with thecalling-keys o 0 of said pair of cords.

The operation of my system is briefly as follows: Assume that thesubscriber at station 1 wishes connection with subscriber at station 2.Subscriber of station 1, his telephone being on the switch, turns hisgenerator sending-current from the ground branch containing thegenerator at his station over the portion of line a connected with theinsulated frames or test-pieces of the switches b 0 through theindividual annunciator d and thus throws down the shutter of saidannunciator. Assume the individual annunciator d to be placed upon thesecond boardthat is, the board supposed to contain the switches c g ofthe two lines. The operator seeing the individual annunciator d fallimmediately inserts plug 1' into switch 0 and depressing listening-key Zreceives the order of subscriber of station 1. It will be understoodthat the subscriber at station 1 immediately takes down his telephoneafter operating his generator so as to bring his telephone into circuitto be in position to communicate with the operator when the operatordepresses lis tening-key Z. The operator having inserted plug t' intoswitch 0 and depressed her listening-key Z will be in communication withthe subscriber of station 1. The act of inserting plug 2 in switch 0serves also to close the circuit of battery 19 through individualannunciator d, this battery 19 being connected, as shown, with the pairof cords. The current of this battery thus sent through annunciator (1will be strong enough to cause the soft-iron drop 1) to be held up,although the other armature 19 will be at the same time attracted so asto raise the hook or detent p to disengage the same from soft-ironarmature-drop 19. Therefore, when the operator inserts her plug *6 in aswitch 0 in answering a call she must at the same time restore theindividual annunciator-drop p by hand so that said soft-iron drop willbe in position to be attracted by the electromagnet. The call will beanswered in the usual way. I11 this instance, subscriber 1 having askedfor subscriber 2, the operator on learning that line e is wanted willfirst apply the tip of plug to the test-ring of switch g to test in theusual manner, and in this instance we will assume that she finds nocurrent present on line 6 and so inserts plug 7c into switch 9, asshown, and depresses calling-key n to throw current from thecalling-generator 0 upon the line 6. Subscriber 2 receiving the calltakes down his telephone and thus subscribers 1 and 2 are connected forconversation, as illustrated in the drawing.

It will be observed that a clearing-out annunciator is included in thecircuit or rather bridged between the strands of the cords, as shown. Acondenser is preferably included in the bridge-wire to prevent thebattery p from sending current through the clearing-out drop to the tipof the plug and thence over the line to earth at sub-station. Thecurrent from battery 19 will also be present on line 6. The current fromthis battery thrown upon line 6 will be so strong that the individualannunciator h will not be thrown down. This battery 19 not only acts asa retaining-battery for the individual annunciators, but serves to throwcurrent into the test portion of the connected telephone-lines, so thatwhen a test is made of a busy line at another board, batterycurrent willbe found present. Thus, at the first board, the tip of plug r is shownapplied to the test-piece of switch f, and current being present on saidline a, battery-current will be directed through the operators telephone8 to ground.

Having thus described my invention, I claim as new and desire to secureby Letters Patent- 1. An electric annunciator provided with twoindependently pivoted armatures, one armature carrying a hook or detentadapted to engage with and retain the other armature, which serves as adrop or target, the armature carrying the hook being adapted to beoperated by a less current than is required to operate and retain inposition the armature which serves as a target.

2. The combination with an annunciator adapted to respond to a feeblecurrent, but to be retain ed unresponsive by a strong current, of acircuit containing said annunciator and a source of feeble current and asource of strong current adapted to be short circuited through saidannuneiator, and a portion of said circuit, substantially as described.

3. The combination with an annunciator provided with two armatures, oneprovided with a hook adapted to engage with and retain the other, of twosources of current, one of sufficient strength to cause the attractionof both armatures, the other being adapted to cause the operation of theretaining armature only, and means for directing current from either ofsaid sources through the electro magnet; substantially as described.

4. In combination with a telephone line, an electromagnet controllingtwo armatures, an indicator adapted to be actuated by one of saidarmatures when attracted and to be retained irresponsive by the other ofsaid armatures when attracted, a source of signaling current connectedwith the telephone line, and a source of continuous current alsoconnected therewith, substantially as described.

5. I11 combination with a telephone line circuit, an annunciatorcomprising an electromagnet, two armatures therefor, one controlling anindicator, and the other adapted to prevent the operation of theindicator when unattracted, and a battery adapted to be connected withthe line circuit to find circuit through the annuneiator, substantiallyas described.

6. The combination With a telephone line In Witness whereof I hereuntosubscribe my circuit, of an electromagnet connected therename this 12thday of February, A. D. 1892. with, two armatures for said electromagnet,an indicator controlled by one of the arma- CHARLES E. SORIBNER.

5 tures to be actuated thereby, the other armature being adapted toprevent the operation Witnesses: of said indicator when it is attracted,substan- M. JANE TALLETT, tially as described. FRANK R. MCBERTY.

